The depiction of chemistry on stamps began in 1923 with the issue of a set of definitive French stamps commemorating the chemist and microbiologist Louis Pasteur.^[1] Another early chemical stamp depicted the botanist and chemist Herman Boerhaave.^[2] The depiction of chemistry on stamps contributes to chemical education^[3][4] and to the public understanding of science.^[5][6]

A chemical stamp has one or more of the following characteristics:

• It depicts a chemist, or a polymath who did significant work in the chemical field
• It depicts a chemical concept, such as the periodic table, or a chemical object, such as laboratory glassware
• It depicts a chemical element,^[7] atom,^[8] molecule, symbol or formula
• It commemorates a chemistry event, such as an international congress, or an international year in the chemical field^[9]
• It celebrates the jubilee of a chemistry institution, such as IUPAC or the American Chemical Society^[10]
• It depicts the process of chemistry education, or a building used primarily for chemistry research or education

Stamps may depict a specific area of chemistry such as physical, analytical,^[11] spectroscopic,^[12] organic,^[13] or inorganic.

The following types of material are excluded (although they may also be collected by chemical stamp enthusiasts):

• Postal stationery,^[14] e.g. a postcard depicting a chemist with a non-chemical stamp affixed
• Cinderella, local, private or personal issues, i.e. unofficial stamps
• Non-postal stamps, e.g. revenue stamps^[15]
• Stamps issued by non-existing/unrecognized countries and/or in excess of actual postal requirements

• 
  Alfred Nobel, Sweden, 1946
• 
  Pierre Curie, USSR, 1956
• 
  Dmitri Mendeleev, USSR, 1969
• 
  A.I. Virtanen, Finland, 1980
• 
  Marie Curie, Albania, 1989

Stamps depicting individual chemists are often issued by countries to commemorate the birth or death anniversaries of their significant national chemists,^[16] for example stamps issued by Russia celebrating Dmitri Mendeleev. Examples are illustrated in the gallery above. Some countries have also issued stamps depicting internationally famous chemists such as Marie Curie^[17][18] or Alfred Nobel.

• 
  Chemical industry, USA, 1951
• 
  Rutherford Scattering, USSR, 1971
• 
  Laboratory glassware, USA, 1976
• 
  Nuclear fission, Germany, 1979

Stamps depicting a chemical concept or object, sometimes combined with a portrait of the chemist responsible for inventing the concept or object, are generally issued as commemorative stamps rather than definitive stamps. Examples are shown in the gallery above: a 1951 American stamp illustrating chemical industry and also celebrating the diamond jubilee of the American Chemical Society,^[10] a 1971 Russian stamp illustrating Rutherford Scattering, a 1976 American stamp depicting Laboratory glassware, and a 1979 German stamp illustrating nuclear fission and also commemorating Otto Hahn's 1944 Nobel prize in chemistry.

• 
  Benzene, Germany, 1964
• 
  IUPAC, USSR, 1965
• 
  Gold, Uzbekistan, 2008
• 
  Tellurium electron shell, Romania, 2011
• 
  International Year of Chemistry, Indonesia, 2011

Stamps depicting a chemical symbol or formula are frequently depicted together with the chemist they are primarily associated with. Examples are shown in the gallery above: a 1964 German stamp illustrating the benzene structure associated with August Kekulé, a 1965 Russian stamp commemorating the 1965 IUPAC meeting in Moscow, a 2008 Uzbeki stamp illustrating the element gold, a 2011 Romanian stamp depicting the electron structure of Tellurium and the chemist F.J. Müller, and a 2011 Indonesian stamp issued for the International Year of Chemistry.

The chemists Edgar Heilbronner and Foil Miller published the book A philatelic ramble through chemistry in 1998 (reissued in 2004)^[19] which was well reviewed.^{[20][21][22][23]} Prior to this, Foil Miller and George Kauffman had published a series of articles on Alfred Nobel, and on Nobel Laureates in Chemistry in The Journal of Chemical Education.^{[24][25][26][27]}

Daniel Rabinovich is the current leading writer in the field having published articles on the International Year of Chemistry,^[17] the International System of Units,^[28] the International Year of the Periodic Table,^[29] Roald Hoffmann,^[30] and also making presentations on the subject to chemistry departments and at chemistry conferences.^[31]

The Chemistry and Physics on Stamps Study Unit (CPOSSU) of the American Topical Association has published a members' journal Philatelia Chimica et Physica since 1979.^[32]

Listings of new issues of chemical stamps are included in the monthly Scott Stamp magazine and in Linn's Stamp News; they are also available online from October 2010 to date in the Science & Technology section.^[33]

• Rabinovich, Daniel (2020). The world of chemistry on postage stamps